Download The Older Adult

CHAPTER 3
Life Span Considerations
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Winter 2013
Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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Life Span
Considerations
Pregnancy
 Breast-feeding
 Neonatal and pediatric
 Older Adult
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Pregnancy
First trimester is the period of
greatest danger for druginduced developmental defects
 Drugs cross the placenta by
diffusion
 During the last trimester, the
greatest percentage of
maternally absorbed drug gets
to the fetus
 FDA has implemented
pregnancy safety categories
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US Food and Drug Administration Drug
Categories Regarding Pregnancy
A - Adequate studies in pregnant women demonstrate no
risk to the fetus
B - Animal studies indicate no risk, but there are no
adequate studies in pregnant women; or animal
studies show adverse effects, but adequate studies in
pregnant women have not demonstrated a risk
C - A potential risk; these drugs may be used when
potential benefits outweigh the potential risks
D -There is evidence of human fetal risk, but potential
benefits to mother may be acceptable despite risk
X -Teratogenic or abortifacients; risk in pregnant woman
clearly outweighs any possible benefit
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Breast-feeding
Breast-fed infants are at risk
for exposure to drugs
consumed by the mother
 Consider risk-to-benefit ratio
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Neonatal and Pediatric
Considerations:
Pharmacokinetics

Absorption
◦ Gastric pH less acidic
◦ Gastric emptying slowed
◦ Intramuscular absorption faster
and irregular
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Neonatal and Pediatric
Considerations:
Pharmacokinetics (cont’d)

Distribution
◦ The younger the person, the
greater the percentage of total
body water
◦ Greater total body water means
lower fat content
◦ Decreased level of protein binding
◦ Immature blood-brain barrier—
more drugs enter the brain
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Neonatal and Pediatric
Considerations:
Pharmacokinetics (cont’d)

Metabolism
◦ Liver immature, does not
produce enough microsomal
enzymes
◦ Older children may have
increased metabolism, requiring
higher doses than infants
◦ Other factors
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Neonatal and Pediatric
Considerations:
Pharmacokinetics (cont’d)

Excretion
◦ Kidney immaturity affects
glomerular filtration rate and
tubular secretion
◦ Decreased perfusion rate of the
kidneys may reduce excretion of
drugs
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Factors Affecting Pediatric
Drug Dosages
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Skin is thin and permeable
Stomach lacks acid to kill
bacteria
Lungs have weaker mucus
barriers
Body temperatures less well
regulated, and dehydration
occurs easily
Liver and kidneys are immature,
impairing drug metabolism and
excretion
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Methods of Dosage
Calculation for Pediatric
Patients

Body surface area method
◦ Using the West nomogram
Always use weight in
kilograms, not pounds
 Body weight dosage
calculations

◦ Using mg/kg
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The Older Adult
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Older Adult: older than age 65
Use of over-the-counter
medications
Increased incidence of chronic
illnesses
Sensory and motor deficits
Polypharmacy
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 Young
Adult 20 – 40
 Middle Adult 40 – 65
 Later Adult >65
Stages of Aging
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 Sources
Adults
of Difficulty for Older
 Use of OTC medications
 Increased incidence of chronic
illnesses
 Polypharmacy
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Physiologic Changes
in the Older Adult Patient
Cardiovascular
 Gastrointestinal
 Hepatic
 Renal
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The Older Adult:
Pharmacokinetics

Absorption
◦ Gastric pH less acidic
◦ Gastric emptying slowed
◦ Movement through GI tract
slowed
◦ Blood flow to GI tract reduced
◦ Use of laxatives may
accelerate GI motility
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The Older Adult:
Pharmacokinetics (cont’d)

Distribution
◦ Lower total body water
percentages
◦ Increased fat content
◦ Decreased production of
proteins by the liver, resulting
in decreased protein binding of
drugs (and increased
circulation of free drugs)
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The Older Adult:
Pharmacokinetics (cont’d)

Metabolism
◦ Aging liver produces fewer
microsomal enzymes, affecting
drug metabolism
◦ Reduced blood flow to the liver
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The Older Adult:
Pharmacokinetics (cont’d)

Excretion
◦ Decreased glomerular filtration
rate
◦ Decreased number of intact
nephrons
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The Older Adult:
Problematic Medications
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Analgesics, including NSAIDs
and opioids
Anticoagulants
Anticholinergics
Antidepressants
Antihypertensives
Cardiac glycosides (digoxin)
Sedatives and hypnotics, CNS
depressants
Thiazide diuretics
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